Offroad vehicles or "ATVs" as they are commonly referred to are designed to be operated over rugged terrain. These vehicles are often operated on steep inclines and declines, on rough roads, and in mud and water.
These vehicles include a frame supported by wheels. In one common arrangement, the vehicle has four wheels. An internal combustion engine is used to power at least one, and most commonly all, of the wheels.
In this arrangement, a first drive shaft extends to a front axle and a second drive shaft extends to a rear axle. Each of these drive shafts extends generally parallel to a centerline of the vehicle extending in the front and rear directions.
The first and second drive shafts are driven by a crankshaft of the engine. The vehicle includes a transmission through which the first and second drive shafts are powered by the crankshaft.
It is very desirable for the engine and related drive train of the vehicle to have a compact arrangement. In particular, due to the conditions in which these vehicles are operated, a great deal of vehicle stability is desired. This stability is enhanced by providing the vehicle with a low center of gravity and a center of gravity which is near the center of the vehicle. In this manner, the vehicle is less likely to overturn.
To facilitate this goal, the engine is often arranged so that the crankshaft extends transverse to the longitudinal centerline of the vehicle. In this arrangement, the center of gravity of the engine is near the centerline of the vehicle, and the periphery of the engine does not extend far from this centerline.
On the other hand, this arrangement has the drawback that the rotation of the crankshaft must be transmitted to the first and second drive shafts which are arranged transverse to the crankshaft. The transmission is thus larger than when the engine is arranged with its crankshaft extending parallel to the drive shafts, with the transmission extending to one side of the vehicle some distance, offsetting some of the benefits realized by positioning the engine transverse.
It is an object of the present invention to provide an offroad vehicle with an engine having a transversely extending crankshaft, where the vehicle has a compact drive layout.